Hardening of metal surfaces



May 9, I939. H. H, BEENY 2,157,948

Fg 2 [1112mm ATTORNeyS.

Patented May 9, 1939 PATENT OFFICE 2,157,948 HARDENING F METAL SURFACES Herbert H. Beeny, Coventry, England, assignor to The Monarch Machine Tool Company, Sid-.

ney, Ohio Application June 17, 1937, Serial No. 148,754

' In Great Britain April 16, 1937 4 Claims.

This invention relates to the treatment of ferrous surfaces such as are capable of being hardened by being locally heated by means of a burner to a high temperature and then immediately cooled. The flame is progressively applied to the surface at a predetermined rate, the arrange- ;ment being such that-there is not suflicient'time for the heat to be conducted awayto the interior of the article before the. surface of the latter is l0 quenched.

The specification accompany ng the co-pending patent application of myself and Arthur H. Lloyd, Serial No. 148,752 describes a particularly satisfactory burner and cooler for treating a fer- 16 rous (for example, a cast-iron) surface in this way, and also an improved form of burner.

It is now'found that in treating the surface of a cast-iron V'-rail in this way there is a tendency for cracks to, form along the apex of the 20 rail. This is probably due to the fact of the flames, acting on the flanks of the rail, heating the apex of the rail to too. great an extent; this resulting in the apex of the rail being hardened to a greater depth than the flanks of the rail.

When a V-rail is to be used as an inverted-V-rail for supporting a machine-tool slide, it is unnec-. essary for its apex to be hardened as the load is taken by the flanks of the-rail.

The present invention is concerned with the surface-hardening of the operative face of a V-rail, to be used for supporting a machine-tool slide or some other slide, by flame-heating the flanks of the 'rail and immediately thereafter cooling them, as specified above; and it involves means acting toprevent the apex of the rail from being hardened in this manner so that the hardened flanks of the rail will be separated from one another by a relatively softsurface along the apex of the rail. Preferably the said means includes aiet of water or other cooling medium arranged to impinge on the apex of the rail in the vicinity of where the flanks are being flameheated, the said jet preferably being directed backwardly. Conveniently the cooling medium 45 from this jet is delivered at a higher pressure than that from the main jets.

In the accompanying diagrammatic drawing:- Figure l is a perspective View of an inverted. V-rail, for .a lathe-bed, in association with a 5 surface-hardening apparatus in accordance'with the invention; and

Figure 2 is a cross-section of the rail indicating the result of the surface-hardening.

' The drawing shows an elongated burner ill of 55 the kind described in the specification abovementioned, the burner having limbs H, H inclined to'one another according to the inclination of the flanks l2, H of the V-rail. It is secured by means of the union [3 to the main fuel supply pipe M. The latter passes through lugs i5, i5, 5 which are bolted to one another at lb, of a tray i1- built up of halves. Cooling liquid is supplied under pressure by a pipe it, which also passes through the tray IT, to a; balance chamber l9 fromwhich are two pairs of cooling pipes 20, 2G 10 directing the cooling liquid on to the respective flanks of the rail in the manner described in the specification above-mentioned. Outlet pipes 23 from the balance chamber carry surplus liquid to the tray, whence it can exhaust by the outlet 22. In addition, thepipes 23 carry cooling liquid at a higher pressure to the burner for interiorly cooling the latter, the outlet pipes therefor being marked it and 25. The outlet pipe 251 exhausts where convenient, but the outlet pipe 25 is in this instance bent round as shown, the end 2%; of the pipe lying substantially in the plane of the two fuel jets 2i and being directed rearwardly.

The pressure delivered from the nozzle end 2% of the pipe is greater somewhat than that 25 delivered from the nozzles of the main cooling pipes 2ll,'and the pressure is regulated to be sufficient to cause a film of water to flow along the part of the apex of the rail in the vicinity of the flames on either side, thus preventing the apex from becoming heated by the combined flames. The result is that only the two flanks are hardened, as indicated at 28, 28 in Figure 2, and this is an arrangement which is perfectly satisfactory as it is only the two flanks which carry the load.

The controls for regulating the respective pressures of the cooling pipes 20 and 25, and the combustible mixture, are not here shown. It will be understood that the main supply pipes may be clamped to one another as desirable and supported, with the various control means, from any convenient support which is adjustable and capable of being-fed to carry the burner and coolers along the rail at the predetermined rate.

In this way it is possible to harden the operative surface of a cast-iron inverted-V-rail-for use insupporting a machine-tool slide in a very satisfactory manner.

What I claim as my invention and desire to secure by Letters Patent of the United States l. A method of surface-hardening only the inv clined flanks of a ferrous inverted-V rail, tube V used for supporting a'slide, which involves flameapex of the rail.

2. A method of surface-hardening only the in- 1 clined flanks of a ferrous inverted-V rail, to be used for supporting a slide, which involves flameheating the flanks of the rail while directing a jet of cooling medium on to the apex of the rail adjacent the flanks in a direction rearwardly of the direction of flame travel, and immediatelycooling theflanks after they have been heated, whereby the hardened flanks will be separated from one another by a relatively soft surface adjacent the apex of the rail.

3. Apparatus for use in surface-hardening the 20 inclined flanks of a ferrous inverted V-rail, to beused for supporting a machine-tool slide, including flame jets for flame-heating the flanks to a high temperature, jets of cooling medium directed on to "saidflanks for immediately cooling the flanks after they have been heated, and a higher pressure jet of cooling medium directed'to the apex of the rail in the vicinity of where the flanks are being flame-heated, whereby the apex is protected from'heat hardening during the heating of the said-flanks.

4. Apparatus for use in surface-hardening only the inclined flanks of a ferrous inverted-.V 'rail, to be used forsupporting a slide, and including a burner with divergent limbs inclined accord-' ing to the inclination of the flanks and adapted to heat said flanks, a cooling system associated therewith and adapted to supply a cooling medium to said flanks subsequent to their heating, and means for preventing the heat hardening of the apex of said rail and comprising a jet of said cooling medium directed on to the apex of the rail in the vicinity of the point of contact between said flanks and a heating flame, whereby the apex of said rail is preserved in a substantially unhardened condition during the hardening of said flanks.

HERBERT H. BEENY. 

